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Date：05-09-2022
The high-voltage load switch fully adopts the arc-extinguishing advantages of the vacuum switch tube and the corresponding operating mechanism. Since the high-voltage load switch does not have the ability to break short-circuit current, it is relatively simple in structure and suitable for occasions with small current and frequent actions. There are two common high voltage load switches: indoor type and outdoor column type.
There are many types of high-voltage load switches, and the structure can be divided into oil high-voltage load switches, vacuum high-voltage load switches, sulfur hexafluoride high-voltage load switches, gas-producing high-voltage load switches and compressed air high-voltage load switches, etc.; according to the operation mode, it is divided into manual operation There are two types of high-voltage load switches and electric high-voltage load switches. These products are concentrated in the distribution network, such as ring network cabinets. At present, vacuum high-voltage load switches are more popular, and high-voltage load switches are equipped with fuses and other equipment. More and more attention has been paid to the advancement of the network transformation work. The following describes the structural characteristics and basic principles of two typical high-voltage load switches.
The high voltage load switch is completely installed on its fixed bracket. Its operating mechanism shall operate in the specified manner, and in particular, if the operating mechanism is electric or pneumatic, its operation shall be carried out at minimum voltage or minimum air pressure, respectively, unless the interruption of the current will affect the test results. In the latter case, the voltage or air pressure during operation of the load switch should be selected within the specified range so as to have the highest speed and maximum arc-extinguishing performance when the contacts are separated. It should be shown that the switch-disconnector operates satisfactorily under no-load conditions under the above conditions. If possible, data such as moving contact travel should be recorded. Non-manually operated load switches can be operated by means of remote control closing.
1. Appropriate consideration should be given to the selection of the connection of the live side. When the load switch is intended to be connected to power from both sides, and the actual layout of one side of the load switch is different from the layout of the other side, the power supply of the test circuit should be connected. to the side that reflects the most severe operating conditions of the load switch. In case of doubt, part of the operation should be carried out with the power connected to one side of the load switch, and another part of the operation should be carried out with the power connected to the other side of the load switch.
2. The making and breaking test of the three-pole high-voltage load switch operated at the same time by each pole shall be carried out on three-phase unless otherwise specified.
The making and breaking test of the three-pole switch with pole-by-pole operation (composed of three single-pole high-voltage load switches) shall be carried out with single-phase, except for the capacitive load breaking test with special requirements.
3. Except for load switches filled with liquid or gas and vacuum load switches, if there is significant flame or metal particle scattering, it may be required to use a metal screen to be placed near live parts and away from them during the test. Factory specified safety clearance distance. Metal screens, brackets and other normally grounded parts should be insulated from the ground and connected to each other and then connected to a suitable grounding device to indicate whether there is significant leakage current to ground.
